L1 cache

The smallest, fastest cache, closest to the processor's execution units; each core has its own, usually one for data and one for instructions.

The level-1 cache is a per-core cache, split into an instruction cache and a data cache (typically 32-64 KB each on x86-64 cores, 128 KB or more on Apple P-cores), with a load-to-use latency of about 4-5 cycles.